Measles vaccine is a vaccine that is very effective at preventing measles.[1] After one dose 85% of children nine months of age and 95% over twelve months of age are immune.[2] Nearly all of those who do not develop immunity after a single dose develop it after a second dose. When rates of vaccination within a population are greater than 93% outbreaks of measles typically no longer occur; however, they may occur again if rates of vaccination decrease. The vaccine's effectiveness lasts many years. It is unclear if it becomes less effective over time. The vaccine may also prevent against the disease if given within a couple of days of being exposed.[1]

The vaccine is available both by itself and in combination with other vaccines including rubella vaccine, mumps vaccine, and varicella vaccine (the MMR vaccine and MMRV vaccine). The vaccine works equally well in all formulations. The World Health Organization recommends it be given at nine months of age in areas of the world where the disease is common. In areas where the disease is very uncommon giving it at twelve months is reasonable. It is a live vaccine. It comes as a dried powder which needs to be mixed before being given either just under the skin or into a muscle. Verification that the vaccine was effective can be determined by blood tests.[1]

Before the widespread use of the measles vaccine, its incidence was so high that infection with measles was felt to be "as inevitable as death and taxes."[7] In the United States, reported cases of measles fell from hundreds of thousands to tens of thousands per year following introduction of the vaccine in 1963 (see chart at right). Increasing uptake of the vaccine following outbreaks in 1971 and 1977 brought this down to thousands of cases per year in the 1980s. An outbreak of almost 30,000 cases in 1990 led to a renewed push for vaccination and the addition of a second vaccine to the recommended schedule. Fewer than 200 cases were reported each year from 1997 to 2013, and the disease was believed no longer endemic in the United States.[8][9][10] In 2014, 610 cases were reported.[11] Roughly 30 cases were diagnosed in January 2015, likely originating from exposure near Anaheim, California in late December 2014.

The benefit of measles vaccination in preventing illness, disability, and death has been well documented. The first 20 years of licensed measles vaccination in the U.S. prevented an estimated 52 million cases of the disease, 17,400 cases of mental retardation, and 5,200 deaths.[12] During 1999–2004, a strategy led by the World Health Organization and UNICEF led to improvements in measles vaccination coverage that averted an estimated 1.4 million measles deaths worldwide.[13] The vaccine for measles has led to the near-complete elimination of the disease in the United States and other developed countries.[14] It was introduced in 1963.[15] These impressive reductions in death and long-range after-effectiveness were initially achieved with a live virus version of the vaccine that itself caused side effects, although these are far fewer and less serious than the sickness and death caused by measles itself. While preventing many deaths and serious illnesses, the live virus version of the vaccine did cause side effects in a small percentage of recipients, ranging from rashes to, rarely, convulsions.[16]

Measles is common worldwide. Although it was declared eliminated from the U.S. in 2000, high rates of vaccination and excellent communication with those who refuse vaccination are needed to prevent outbreaks and sustain the elimination of measles in the U.S.[17] Of the 66 cases of measles reported in the U.S. in 2005, slightly over half were attributable to one unvaccinated individual who acquired measles during a visit to Romania.[18] This individual returned to a community with many unvaccinated children. The resulting outbreak infected 34 people, mostly children and virtually all unvaccinated; 9% were hospitalized, and the cost of containing the outbreak was estimated at $167,685. A major epidemic was averted due to high rates of vaccination in the surrounding communities.[17]

The live vaccine has non specific effects such as preventing respiratory infections that may be greater than those of measles prevention. These benefits were greater when used before a year of age. A high titre vaccine resulted in worse outcomes in girls and thus is no longer recommended by the world health organization.[19] As measles causes upper respiratory disease that leads to complications of pneumonia and bronchitis, measles vaccine is beneficial to control exacerbations of chronic obstructive pulmonary disease (COPD) and asthma.

Adverse effects associated with the MMR vaccine include fever, injection site pain and, in rare cases, red or purple discolorations on the skin known as thrombocytopenic purpura, or seizures related to fever (febrile seizure).[20] Serious side effects are extremely rare.

As a fellow at Children's Hospital Boston, Dr. Thomas C. Peebles worked with Dr. John Franklin Enders. Dr. Enders became known as "The Father of Modern vaccines", and Enders shared the Nobel Prize in 1954 for his research on cultivating the polio virus that led to the development of a vaccination for the disease. Switching to study measles, Enders sent Peebles to Fay School in Massachusetts, where an outbreak of the disease was under way, and there Peebles was able to isolate the virus from some of the blood samples and throat swabs he had taken from the students. Even after Enders had taken him off the study team, Peebles was able to cultivate the virus and show that the disease could be passed on to monkeys inoculated with the material he had collected.[14] Enders was able to use the cultivated virus to develop a measles vaccine in 1963 based on the material isolated by Peebles.[28] In the late 1950s and early 1960s, nearly twice as many children died from measles as from polio.[29] The vaccine Enders developed was based on the Edmonston strain of attenuated live measles virus, which was named for the Fay student from whom Peebles had taken the culture that led to the virus's cultivation.[30]

Dr. Maurice Hilleman at Merck & Co., a pioneer in the development of vaccinations, developed the MMR vaccine in 1971, which treats measles, mumps and rubella in a single shot followed by a booster.[16][32] One form is called "Attenuvax" with more than 40 peptide sequences.[33] The measles component of the MMR vaccine uses Attenuvax, which is grown in a chick embryo cell culture using the Enders' attenuated Edmonston strain. Merck decided not to resume production of attenuvax on October 21, 2009.[34]

MMR is not generally given to children less than 12 months of age. However, the CDC recommends that infants aged 6 to 12 months traveling outside the United States receive their first dose of MMR vaccine.[35] Pediatric dosing is 0.5 ml subcutaneously (often between 12–18 months). A second dose is given by 7 years (on or before last day of year 6) or by Kindergarten entry.[36] Vaccine is administered in the outer aspect of the upper arm. In adults, 0.5 mL subcutaneously and a second dose 28 days apart is given. In adults greater than 50 years, only one dose is needed.